Field of the Invention
The present invention relates to a sheet feeding apparatus and an image forming apparatus including the sheet feeding apparatus.
Description of the Related Art
Known image forming apparatuses in the related art for forming an image on a sheet, such as a printer, a facsimile machine, a copying machine, and a compound machine thereof, include a sheet feeding apparatus for feeding sheets in a cassette to an image forming unit. An example of the sheet feeding apparatus includes an intermediate plate on which sheets are stacked and side regulating members that move in a direction perpendicular to a sheet feeding direction (hereinafter referred to as “width direction”) to regulate the side edges of the sheets. The side regulating members on both sides of the sheets are moved to predetermined positions according to the size of the sheets. Thus, the sheets are positioned.
An example of a method for positioning side regulating members of known sheet feeding apparatuses for regulating the positions of the side edges of sheets is an insertion method for inserting the regulating members into insertion holes formed at predetermined positions. Another example disclosed in Japanese Patent Laid-Open No. 2000-309431 is a sliding method for positioning regulating members on both sides of the sheets, which are connected together with a belt and are slidable only in sheet regulating directions, in the sheet width directions by sliding the regulating members in opposite directions by the same amount of movement.
The insertion method of inserting the regulating members into insertion holes require much time and effort because changing the sheet size needs to detach the regulating members from the insertion holes and again insert the regulating members into other insertion positions at predetermined positions.
Apparatuses using the sliding method are easy to operate since they allows the positions of the regulating members to be changed only by sliding the regulating members, as disclosed in Japanese Patent Laid-Open No. 2000-309431.
However, the apparatuses using the sliding system need to move the side regulating members disposed at the inner part of the apparatuses and opposing an operating unit with an operation on the operating unit and is liable to cause bending at contact portions that are in contact with the side regulating members.
In particular, in a configuration in which a cassette unit can be inserted into and extracted from an apparatus main body, side regulating members are disposed in front of and behind the cassette unit in the drawing direction. Furthermore, an operating unit is sometimes disposed at the front of the cassette unit for ease of operation. In this case, if the user places a large volume of sheets in the cassette unit and closes the cassette unit with strength, the side regulating member at the inner part of the apparatus may be pushed by an inertial force acting on the cassette unit due to the weight of the placed sheet bundle to be bent. When the side regulating member at the inner part of the apparatus is pushed to be bent, it is difficult to properly position the sheet bundle with the side regulating member.